Efforts to improve the lighting efficiency and uniformity, particularly for park, turn, signal, running and signature lamps, which are frequently integrated around headlamps and tail lamps, are an on-going endeavor among Original Equipment Manufacturers (OEM) and the numerous component/system suppliers. Of particular interest is the desire to propagate the light as uniformly as possible. The present invention is directed one such innovation solution to provide a lighting and/or signaling device which can produce efficient and uniform light beam.
Lighting devices, particularly for vehicles, have many stringent requirements, particularly concerning lighting efficiency and uniformity, particularly for park, turn, signal, running and signature lamps. These lighting devices includes a light guide to provide different lighting and/or signaling functions.
Conventional light guiding devices have a relatively simple structure, but the uniformity of light diffusion is somewhat restricted. In particular, in applications involving multiple light sources (LEDs), the uniformity of the light that has passed through the light guiding device is often unsatisfactory. In some conventional light guiding devices, optical couplers are used to couple the light guide and a collimator. Further, the light sources are positioned in such a way that the direction of emission of the LEDs is perpendicular to an optical axis of the headlamp. Majority of the light rays propagate from a light entry side of the light guide to the light exit side of the light guide by the principal of total internal refection. Because of the design of the optical couplers, some of the light rays may reach to the light exit side of the light guide without undergoing any diversion and/or reflections, thus causing high luminous intensity points, also called hotspots. An observer when viewed from a side of the vehicle may perceive these hotspots. To this observer, the light guide has a look out along its length with brighter points appearing at the location of the optical couplers. The hotspots produce an unaesthetic effect that disturbs the homogeneity of the emitted light beam. The invention herein overcomes one or more of the problems of the known light guiding devices.